This is the 5179th most frequent Japanese word.
重ねる
"重ねる" means "to stack, pile up, layer, or repeat."
In this sentence, "重ねる" (to pile up or accumulate) is used in the sense of progressively gaining more experience over time.
経験を重ねることで、成長します。
By accumulating experience, one grows.
Here, "重ねる" conveys the literal action of physically stacking objects on top of one another.
箱をいくつも重ねて置いた。
I stacked multiple boxes.
In this case, "重ねる" illustrates the idea of continuously repeating an activity, such as discussions, to achieve a result.