数を数える

to count

→ 数
phrase Rare #42,311
to count Literally means “to count numbers.” It is used for counting numbers or things; the object being counted can be specified with の数, as in 星の数を数える (“to count the number of stars”).
JA: 彼は数を数えることができない。
EN: He cannot count.

私は空にある数を数えることができない

I can't count the number of stars in the sky.