I'm a novice and I apologize if the question is ordinary:
What does it means when in sketch mode i see "a blue funnel" near the pointer and i cannot select anything?
you have enabled filters, use F6 to turn them of.
Use F5 to switch the filter bar on/off and play with it -this is really useful.
2014 SOLIDWORKS Help - Selection Filter
so it represent the fact I cannot select entities cause I have some active filter, right?
But how come did it appears? what's its function?
You could have accidentally turned some of them on e.g. by pressing e,x,v.
Filters are a good selection tool, and may be used in many cases not only in the sketch.
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