It's a figurative (i.e. not literal) expression which means "to overwhelm". It can be used both in a positive and negative sense.
Blow, in a literal sense, can take form as a noun, which can mean a hit or strike on someone or something (e.g. I took a blow to the head). As a verb, blow would usually mean to produce a current of air (e.g. the wind blows or blow air through your mouth).
Of course, this is not a comprehensive list as the word 'blow' can be used in a whole range of contexts.