我会说汉语
I can speak Chinese

我会说汉语。我会开车。我不会跳舞。

会 is the 'I learned how' word. It stands in front of the main verb and says you once acquired the skill and still have it: 我会说汉语, 我会开车, 我会游泳. Its negative is always 不会, never 没会 — a skill is a standing fact about you, and 没 denies only events. Listen to the sandhi as you say it: 会 falls, so the 不 in front of it rises, bú huì.

明天会下雨。

The same 会 has a second job: it says something is likely. 明天会下雨 is 'it's going to rain tomorrow' — and nobody ever learned how to rain. Which job 会 is doing is decided by the sentence around it: with a person and a skill verb it means 'can', and with weather, or with anything that simply happens to happen, it means 'will, probably'. One small word carries both, and in practice you will not confuse them.

你会不会游泳？会一点儿。

Ask about a skill in either of two ways: 你会游泳吗 or 你会不会游泳. The second puts the positive and the negative side by side, and inside that frame the 不 goes light and toneless — huì bu huì. The answer is the bare modal: 会, 不会, or the modest 会一点儿, 'a little'. Notice too that 游泳, 开车, 唱歌 and 跳舞 are each a verb glued to its own object; take them whole for now, and never add another object after them.

你会做什么？我会说汉语，我会游泳，我不会开车。明天会下雨吗？

Say three things you can do and one you cannot, out loud: 我会…, 我会…, 我会…, 我不会…. Then put the A-not-A question to a friend — 你会不会… — letting the 不 in the middle go light and toneless. Finish with one guess about tomorrow's weather: 明天会下雨吗.