This is one part out of ten equal parts. (See: [[rc://en/ta/man/translate/translate-fraction]])
# a tenth of an ephah
This can be written in modern measurements. AT: "a tenth of an ephah (which is about 2 liters)" or "2 liters" (See: [[rc://en/ta/man/translate/translate-bvolume]])
# a grain offering of jealousy
"a grain offering for jealousy"
# indicator of sin
An "indicator" is something that shows evidence of something. In this case, he made the offering to determine whether his wife had committed adultery or not.