find one's legs不是“找到某人的腿”吗？

这里的legs也可以换成feet。这个短语的真正含义如下：

1.指婴儿或人等会站立，会走。

My daughter found her legs at her 10th month.

我女儿10个月时就会走路了。

That child has not yet found his legs.

那个小孩仍未能站立。

find one's legs也可以说feel one's legs。

The baby felt her legs not long after she could speak.

这婴儿在会说话不久就会走路了。

2.find one's legs比喻开始认识自己的能力，有了自信；适应。

Anna didn't find her legs. until she made a three-pointer.

安娜直到投进一个三分球才有了自信。

You will find your legs if you keep on.

你如果坚持会找到自信的。

Sea legs原系航海用语，指的是颠簸的船上能平稳行走而不晕船的能力。后来，被人们用来比喻“适应新环境”。

3.find/get/have one's sea legs, 都用来比喻“适应新环境”。

Sea legs原系航海用语，指的是颠簸的船上能平稳行走而不晕船的能力。后来，被人们用来比喻“适应新环境”。

It took me a while to find my sea legs, but I feel fine now.

我花了好长一段时间才适应新环境，现在好多了。

I will help youfind you sea legs.

我会帮助你适应新环境的。

当然，find/get/have one's sea legs也指适应或习惯海（水、船）上（颠簸）生活

After several days on board, I found my sea legs and no longer felt seasick.

我在船上过了几天，就习惯了颠簸，再也不怕晕船了。

The northerners had not yet found their sea legs.

这些北方人，还不习惯水上的颠簸。

It won't take you long to find your sea legs.

不用多久你就会习惯船上生活。

《牛津高阶英汉双解词典》

find/get their ice legs懂得溜冰；学会溜冰