This is the 10260th most frequent Russian word.
боишься
"Боишься" means "you are afraid" in English.
Here, 'боишься' is used to indicate fearing something specific.
Почему ты боишься темноты?
Why are you afraid of the dark?
In this sentence, 'боишься' expresses a general feeling of fear.
Если ты боишься, то можешь позвонить мне.
If you are scared, you can call me.
'Боишься' here refers to the fear of taking on new challenges or actions.