なら、貸してあげるよ

if you want it, I'll lend it to you

→ だ
phrase Rare #35,683
if you want it, I'll lend it to you A conversational offer meaning that the speaker will lend something if the listener wants or needs it. なら sets the condition, and 貸してあげるよ means “I’ll lend it to you.”
JA: その傘が必要なら、貸してあげるよ。
EN: If you need that umbrella, I'll lend it to you.

もしお金が欲しいなら、貸してあげるよ

If you need money, I can lend you some.

このペンが欲しいなら、貸してあげるよ

If you want this pen, I can lend it to you.

それ必要ななら、貸してあげるよ

If you need it, I can lend it to you.

その本を汚さないように扱ってくれるなら、貸してあげるよ

I'll lend it to you as long as you handle it carefully and don't get it dirty.

鉛筆がいるなら、貸してあげるよ

If you need a pencil, I can lend you one.