On average a person loses from 50 to 100 hairs per day which is normal even if we don't notice it.
So yes if you're losing a bit of hair when brushing it's normal and nothing to worry about unless you're losing a lot of hair when brushing.
If you lose a lot more hair when brushing or taking a shower then you could have a vitamin deficiency causing the hair loss.
But losing some hair is normal and nothing to worry about. People with longer hair tend to notice it more when they're losing their hair.