“Alot” is not a word. It is a common misspelling of “a lot,” which is an expression that means “many” or “a large amount.” For example:
- I have a lot of work to do.
- There are a lot of people at the party.
“A lot” is always two words, and it is always followed by a noun. For example:
- I have a lot of books.
- There are a lot of people at the party.