Question: Kumusta mga kaibigan! Can anyone explain the modern us

Kumusta!
"Yung" is from "iyong" which is iyon+g=that (not iyo+ng=yours).
E.g.:
- Nakuha mo ba YUNG libro mo? = Did you get THAT book of yours? (literal) / Did you get your book? (simplified)
- Noong nakita ko sila, parang may kakaiba... YUNG [parang] may mali. = When I saw them, something was kinda off... THAT/IT'S LIKE there's something wrong (simplified)
- Ano YUNG sabi mong gagawin mo? = What was IT [that] you said you were going to do? / What was THAT (adding another that is redundant) you said you were going to do?
- Hindi ko naintindihan YUNG sinabi mo. = I didn't understand WHAT you said. (simplified) / I didn't understand THAT THING you said. (literal)
- Pinatay niya na YUNG ilaw. = She/He turned off THE light already. (simplified; as "ang") / She/He turned off THAT light already. (literal; can be mistaken for "iyang")

Mabuti naman, mate! 👍🙂“DenC” gave some possible interpretations of “yung” to guide you as a reader or listener. Context can usually help you decide how to interpret it.What I’ll explain instead are the basic meanings/translations of “iyon”, “ ‘yung ”, and “ang”, which I hope can help you decide which one to use correctly when you are the speaker or the writer.1. IYÓN:“Iyón” is the formal form of the pronoun “that”. It is used as an indicator or a “pointer”. We pronounce it more like “iyun” though, and maybe that’s why its informal form is “ ‘yun ”.IYON/’YUN ay pusa. = Pusa iyon/’yun. = THAT is/was a cat.
IYON/’YUN ang asawa ni Mark. = Ang asawa ni Mark ay iyon/’yun. = THAT is Mark’s wife.2. ‘YUNG:“ ’Yung ” is a peculiar Tagalog word. It is actually “iyon na [that(, who/which)]” that is used as a modifier or a pronoun. As a modifier, what it refers to becomes specific. As far as I know, that’s how we’ve always been using it that there’s nothing modern about it. “DenC” wrote it as just “yung”, which is commonly done in informal writing, but you might see it more often in standard writing to begin with an apostrophe, marking the omission of the “i”.****
Note: In formal writing, it should be “iyon na”, but it is never used that way before the word it modifies, i.e., we use only either “yung” or “ ’yung” before the word it modifies. It is to avoid the possibility of converting it to “iyong” and confuse it with the pronoun/adjective “iyong (iyo na = your)”. So, we’d always say/write, for example: “pusa NA/pusaNG IYON (after “pusa”, to mean “that cat”)” and never as “IYON NA/iyoNG pusa (before “pusa”)” which would be understood instead as “your cat”.The Dictionary on this site has “yung” as an entry and defines it as “the (colloquial); that”. I disagree with the given “the” definition because it is nothing more than just “that (iyon)”, followed by the linker “na”. I guess that’s the reason why the “Diksiyonaryo” site only has an entry for “iyon”, but nothing on “yung” nor “’yung”.
**** ‘YUNG pusa na/pusang itim ‘YUNG tumakbo. = ‘YUNG tumakbo ay ‘YUNG pusa na itim/pusang itim. = THAT(, which is a) black cat was THAT, which ran. ‘YUNG asawa ni Mark ay madaldál. = Madaldal ‘YUNG asawa ni Mark. = THAT(, who is the) wife of Mark’s is talkative.3. ANG“Ang” is the article “the”. In some cases, “ang” may be used in place of “ ‘yung ” and vice versa. That might have been the reason that made you think that one is an alternative to the other. That may be so in many cases, but keep in mind that their literal translations should remain as “the” and “that”. ‘YUNG pusa na/pusang itim ANG tumakbo = THAT(, which is a) black cat, was THE one that ran.ANG pusang itim ‘YUNG tumakbo. = THE black cat was THAT, which ran.However, just like in English, there are cases when replacing one with the other could change the meaning of a sentence.Sino ANG kasama mo kahapon? = (lit. Who was THE one with you yesterday?) Who were you with yesterday? (It could be anyone.)Sino ‘YUNG kasama mo kahapon? = Who was THAT(, who was) with you yesterday? (Suggests that the speaker saw you with a companion and the question is particularly about that other person.)
In summary, imagine two women having a friendly conversation while seated on a park bench. Across, but from a distance, are two guys talking about those women.Guy 1: Kilala mo ba ang MGA IYON? = (lit. Do you know THOSE?) = Do you know them?
Guy 2: ‘YUNG nasa kanan ang asawa ni Mark, di ba? = THAT(, who is) on the right, is Mark’s wife, isn’t she?
Guy 1: Oo, ‘YUN/IYON ang asawa ni Mark. ‘YUNG kausap niya, kilala mo? = Yes, THAT is Mark’s wife. THAT, whom she’s conversing with, do you know who she is?
Guy 2: Hindi ko kilala ‘YUN/IYON. = (lit. I don’t know that). = I don’t know who THAT is.
Guy 1: ‘YUNG nasa kaliwâ ang kabít ni Mark. = THAT(, who is) on the left, is Mark’s mistress. 😨(“Kabít” is a slang word.)
Guy 2: Ano ‘YUN/IYON? = What’s THAT?/Say what? 😲
Guy 1: ANG babae sa kaliwa, ‘YUNG kausap ng asawa ni Mark, ‘YUN/IYON ang kabit ni Mark. = THE woman on the left, THAT, who Mark’s wife is talking with, THAT is Mark’s mistress. 😱🤣 So, just use “iyon”, “’yung”, and “ang” in the same context as you would use “that”, “that, who/which” and “the” in English.

Maraming salamat sa inyo, you guys are legends !!!