This is the 466th most frequent Japanese word.
実
"実" means "reality," "truth," or "fruit/nut" depending on context.
In this sentence, '実' is used metaphorically to mean 'fruit' as a result of efforts or actions.
彼の努力が実を結ぶ日が来た。
The day his efforts bear fruit has come.
Here, '実' is used in its literal sense to refer to actual fruits that grow on a tree.
この木には甘い実がなる。
This tree produces sweet fruits.
In this context, '実' signifies the outcome or achievements resulting from endeavors, similar to 'proof' or 'fruition' of efforts.