That's it.

Could someone let me know what this expression “That’s it” signify? I am wondering if it could imply different meanings depending upon the situation.Is this the same as"That’s all".Please give me some examples so i can understand in what context i should use it.I always need your help and appreciate your kindness. Thanks.

Most literally, “That’s it” means “That (referring to a physical object or abstract thing) is the thing I meant / I was looking for / we were talking about / etc.” More idiomatically, it can be used as an exclamation in various scenarios: when you or someone else has found a solution or answer; when you have finished finished doing something; when you are exasperated with something and decide to stop doing it (or stop someone else doing it); when something has gone badly wrong and there seems no hope.

You are still making simple mistakes with spacing and capitalisation. The word “I” is always capitalised. Spaces are required between sentences. Spaces are required before opening quotes.