How many external HD (not 4K or 5K) displays can I use with the 2016 13" MacBook Pro with Touchbar?
Officially it will support one display at 5120 x 2880 pixels at 60 Hz or up to two displays at 4096 x 2304 pixels at 60 Hz. Of course, this is the 5K and 4K you're probably already aware of.

However, unofficially you could use more than two external displays via various adaptors, at or below the above resolutions. How many you can use will depend on the specs of the actual displays used. Also, you need to be aware that your MBP fans may start spinning at much faster speeds depending on your setup.

You may find the following info of interest to you. While not directly about the 2016 MBP, the info is still relevant.