"There are ten of us."
Translation:Nous sommes dix.
According to google translate "d'entre nous = "of us" :https://translate.google.com/#fr/en/d'entre%20nous
If you're asking if this translates to someone being the age of 10, then no. I believe the way you'd say, "we are 10 years old," is; "Nous avons dix ans," or, "on a dix ans"
If you were just confused about the literal translation, I'm pretty sure it's just the way the french state how many people there are. It's similar to how the french would say, "I have 15 years" instead of, "I am 15 years old". ¯_(ツ)_/¯