This can be stated in active form. Alternate translation: "there are men whom other men have made eunuchs" (See: [[rc://en/ta/man/jit/figs-activepassive]])
Possible meanings are 1) "men who have made themselves eunuchs by removing their private parts" or 2) "men who choose to remain unmarried and sexually pure." (See: [[rc://en/ta/man/jit/figs-metaphor]])
Here "kingdom of heaven" refers to God's rule as king. This phrase is found only in the book of Matthew. If possible, keep "heaven" in your translation. Alternate translation: "so they can better serve our God in heaven" (See: [[rc://en/ta/man/jit/figs-metonymy]])