If you are borrowing something (or somebody), it means that you want to use it (or a person's time) temporarily. When your leader said "Can I borrow you?" the leader was asking if they could borrow your time, having your complete attention for something they wanted to tell you. It was also meant to say that your time was needed and not your female colleague. The leader could have said "Can I talk with you for a little while?"

Often times I see it used as "may I use your skills for a moment?" For example, if I have trouble lifting an object I may say to a stronger individual, "Can I borrow you for a moment?" So in short, either the person is requesting your attention or your assistance.

can i borrow you 我可以跟你说几句吗 可能你的leader是想跟你和你同事 同时谈事 或者你的leader想跟你同事谈事，但不介意你在旁边听着 不必confused,有时候生活中我们经常遇到这个情况;)