One kid having squinting left eyes some time when she tries to see far. If observed closely squinting is not noticable at all. Does this can be treated and how. Please advice?

Nearsighted. Squinting artificially lengthens the eye a little & allows someone to see things at a distance more clearly. This is the problem of the nearsighted(can see ok near).It is likely worse than 20/40 vision which is the level most kids start having trouble seeing the blackboard at school.
Needs Seen. This case needs to be examined by a pediatric opthamologist for eye problems. If left alone, it may get worse.