If I make a website for a client who will update that website. (I mean won't I be busy with other people's website)

Question

Website

Answer 1

Yes, you might be asked by a customer to update the site after creating it.
It is up to you if you want to charge extra for it. I would consider it part of the website construction price if the update was to fix a bug or if it was quick and within a month or so of making their new website public.
Yes, you might be busy with another project but it would be just extra work. Decide if you want to do them and for what price. If you'll do the change, find the time.

Answer 2

Thank you sir for the explanation