Learn French: Je cicatrise vite, c'est parfait. - I heal quickly, it is perfect.

Yes, it means to heal, but it is specifically used for physical wounds, cuts, or tissue forming a scar (une cicatrice). If you are talking about recovering from a general illness like a cold or the flu, you would use the verb guérir instead.

Why do we use c'est here instead of il est for it is?

We use c'est because the word it refers to the general situation or the entire previous statement, which is the fact that you heal quickly. When you are commenting on a whole idea rather than replacing a specific masculine noun, you must use the neutral pronoun ce, which becomes c' before est.

Could I say Je cicatrise rapidement instead of vite?

Yes, absolutely! Vite and rapidement both mean quickly or fast and can be used interchangeably in this sentence. Vite is simply a bit shorter and extremely common in everyday spoken French.

How do I know whether to use vite or rapide here?

You need an adverb to describe how the action of healing happens, so you use vite. In French, vite is an adverb, while rapide is an adjective used to describe nouns, like un train rapide.