As a Man: Cool, fool girl
It is not only OK for a girl who is growing up to have male friends, but it is an essential part of a young woman's development to have relationships with boys who see her as just another person.
So it is quite fine for a wee lass to run with a pack of boys (as the only female in the bunch), even as inevitably one or two decide to 'try a thing' as they grow up.
It is also an essential part of a girl's development to have a good friendship with one boy.
However, there is a huge difference between a young girl being accepted as just another human being by a boy and being respected by the boy pack. There is not a clear-cut definition between the two, and the ideal situation is for a young girl to have both the acceptance and respect of a circle of boys she may end up with. They are not mutually exclusive.
DISRESPECT AND ACCEPTANCE
However, acceptance can come with disrespect and respect may mean rejection from friendship. If, in friendship with a group of boys or one boy, a girl has to choose between acceptance and respect, she had better choose the latter or she will be establishing a pattern of behaviour that is going to take her into those early 20s and 30s, where decisions about partners for (hopefully) the long-term are made. For there is this thing that boys say about girls who confuse being disrespected with being accepted as a friend. They say she is 'cool', and being the 'cool' girl is very often the same as being a 'fool' girl.
When a boy says a girl is cool, it can mean that he sees her as his equal. I have found, though, that it holds true in the minority of cases. For the most part, it means that he can behave any way he wants around her and she accepts it. And it is not even sexual - but the language the boy or boys use when she is around. The 'foul-mouthness' and the way he talks about other people - including other girls he sees as sexual fodder or things to be dissected for their failures to match up to his standards.
The disrespectful boy who thinks a particular girl is 'cool' feels it is OK (and maybe even appropriate) to show her his nastiest side, and she is a fool to believe that this indicates acceptance and even affection.
Amazingly, the 'cool fool' girl does not realise that the other girl who the same boy cannot curse around, but sniffles behind her back that "she gwaan like she better than people," is the one he holds in high regard. She is the one who will grow up to be 'wife material', while the cool chick who accepts disrespectful behaviour is just the one who was also around and is, really, nobody.
The girl who was so cool that the boys could expose the worst of their personalities around her, is very likely to be the one who grows up to be with a man who has absolutely no regard for her and ends up in an abusive relationship, which is not so cool.
I have seen it happen.