A slope, incline, or hill—the inclined part of the ground used to describe uphill or downhill terrain.
この坂は急で、自転車で上るのは大変だ。
This slope is steep, and it's hard to ride up by bicycle.
学校の前に長い坂がある。
There is a long slope in front of the school.
坂を下ると海が見える場所がある。
There's a spot where you can see the sea when you go down the slope.
朝の散歩で坂道を登るのが日課だ。
Climbing the slope on the morning walk is my daily routine.
A figurative use meaning a milestone or turning point in age or life (e.g., 'the hill of 60' for reaching age 60).
彼はもう四十の坂を越えたと言っている。
He says he's already passed the hill of forty (he's past forty).
結婚してから子育ての坂を一緒に乗り越えた。
After getting married, we overcame the parenting 'hill' together.