Learn Arabic (Modern Standard): كيف حالك؟ لا بأس.

In Arabic, present tense sentences usually don't use a "to be" verb (like "am", "is", or "are"). The word حال means "state" or "condition", so instead of saying "How is your state?", Arabic simply puts "How" (كيف) right next to "your state" (حالك).

How do I pronounce حالك depending on who I am speaking to?

The attached suffix ـك means "your". When speaking to a male, it takes an "a" sound: حالُكَ (ḥāluka). When speaking to a female, it takes an "i" sound: حالُكِ (ḥāluki). They are spelled exactly the same way in standard unvoweled writing, so you have to know from context who is being addressed!

What do the words in لا بأس literally mean?

The word لا means "no", and بأس means "harm", "hardship", or "worry". So literally, you are saying "No harm." It is a very common expression used just like "Not bad" or "No problem" in English.

How does the symbol on top of the middle letter in بأس affect pronunciation?

That symbol is a hamza (ء). It represents a glottal stop, which is a brief catch or pause in the back of your throat (like the pause in the middle of the English word "uh-oh"). Because it sits on top of the letter alif, you pronounce the word as "ba's" with a sharp stop, rather than a smooth, long "baas".