Translation:Your cat is pretty.
A comparison is implied any time you don't put an adverb like 很 before an adjective. 很 can mean "very", but it doesn't really intensify the meaning. It just cancels out the implication a comparison.
If you say 他高, by itself, without any context, it seems like you're about to say something else, like "He's tall... but I'm taller." Or "He's tall... but his brother is short."
Which, incidentally, leads to the joke that the phrase "你好" kind of sound like a comparison too. Like "You're fine ...... but I'm better." Or "You're alright ...... but I feel terrible."
So when you want to say "I'm alright, I'm good" you must use 很好 and not just 好 by itself. Same with any other adjective including 高.
非常 does mean 'very' in the context you use it, like 非常好 = very good, but you probably also now that 很 is usually defined as 'very' as a common interpretation in dictionaries. I think it is a strange word in Chinese which seems to mean a lot of things depending on the context in which it is used.
Also number 148 on this list of 3,000 Duolingo Chinese words which I find a great resource:
Yes, 很 means very but not really in this sentence.
In Chinese, some adjectives can act like verbs, These adjectives are always used to describe some traits of a person or things, for example, 高 (tall), 贵 (expensive), 漂亮 (beautiful), etc. 高兴 here is an adjective acts like verb in the sentence. In such case, you need a "很" before the adjective only to make the sentence complete, "很" doesn't really indicate the degree, it is not necessary to translate here.
"很" can be dropped when there is a compare:
Scene: I am happy today but David isn't.
Question: Who is happy today?
In Mainland China, the character with connected strokes is considered the correct character; In Taiwan, the one with 2 separate, open strokes is considered correct. Also the character showing on the screen depends on the encoding codes used and the character set of the reading side. Sometimes it can be very wrong. e.g. 決心 (wrong) vs. 决心. However, you can ignore such small difference without too much problem. It is good to know though for people searching for excellence.
It's not a question of necessity! It's context only
你们的猫... it doesn't tell us how many cats, but it does tell us they're more than a single owner of cats! The point is that there's no distinction in English between plural and singular "you"!
Just keep in mind the sentence idea: Your (plural) cat (or cats) is (or are) beautiful!
Now, just as a side note: translation to English is useless (not completely, of course) in this case... the Chinese version is ambiguous, any English translation would also be ambiguous! But they can never match! They, at best, can share a common ambiguity resolution, a common meaning for a certain context! That's why I don't get all these people talking about English in the comments!
It's strange that 漂 alone means "to drift". I know that associating two characters to make a new one in Chinese does not necessarily follow any kind of logic, but I still wonder how "to drift" was associated with "beautiful". Also, is it correct to use 亮 instead of 漂亮? What's the difference between the two?