seeing how quickly children grow up is really emotional.
It makes me feel really emotional to see children grow up
It really moves me watching children grow up
「子供の[成長](https://eikaiwa.dmm.com/uknow/questions/9560/)を見るのは[感慨深い](https://eikaiwa.dmm.com/uknow/questions/18886/)」= seeing how quickly children grow up is really emotional. / It makes me feel really emotional to see children grow up / It really moves me watching children grow up
ボキャブラリー
emotional = 感情的、感慨深い
grow up = 成長する
quickly = はやく
feel = 感じる
makes me = ~させる
to see/seeing/watching = 見る事
move = 感動する・感動させる
It stirs many emotions in me to see the growth of children
子供の[成長](https://eikaiwa.dmm.com/uknow/questions/9560/)= growth of children, development of children
Xを[見る](https://eikaiwa.dmm.com/uknow/questions/33932/)のは= seeing X, watching X
感慨深い=deeply emotive; moving
「stirs many emotions」は英語の決まったフレーズで感慨深いとほぼ同じ意味です。