I found it surprisingly tricky to say all three of my kids' ages in Japanese in one sentence. The sentences featured in the video are:

4歳と3歳と2歳です。
They're four, three, and two years old.

上の子が4歳で真ん中の子がもうすぐ3歳で下の子がもうすぐ2歳です。
My oldest child is four, my middle child is three, and my youngest child is two.

Also mentioned:
長男 [ちょうなん] (oldest son)
長女 [ちょうじょ] (oldest daughter)
次男 [じなん] (second son)

Didn't mention, but could have also mentioned:
次女 [じじょ] (second daughter)
三男 [さんなん] (third son)
三女 [さんじょ] (third daughter)

Hope you found it helpful!

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