How to use USB wifi adapter on a MacBook Pro running on Mojave
I believe what you are trying to do is called Internet Sharing.

You can not forward your Mac- WiFi to another WiFi, but you can set up sharing.

Important note:
The one big limitation is that you can’t both be connected to a Wi-Fi network and host a Wi-Fi network at the same time. So what you are trying to do with the USB WiFi is not possible using your mac-WiFi.

But you can use Internet sharing if your Mac is connected to the Internet through an Ethernet adapter. 

Enable Internet Sharing and Configure Your Hotspot

The Wi-Fi hotspot option is part of the “Internet Sharing” feature in macOS. 

You’ll find it in the System Preferences window. 

Click the Apple menu, select System Preferences, and click the Sharing icon. Follow the instructions there.