"A lpt friends come to meet him whenever he visits his home town." in this sentence 'friends' is not uncountable. So using 'a lot' is correct or not.? instead of using 'many of/ so many'.

A lot of or lots of mean the same.They can be used before both countable and uncountable nouns. In general,we use much with singular uncountable nouns and many with plural nouns.Also when we use much or many before articles or pronouns (either demonstrative or possessive),of needs to follow.Hence, so many friens or a lot of friends both are correct.(remember using of before articles and demonstrative pronouns)