This is a lye soap used mostly for laundry. It was first introduced in the early 1900s. In 1928 Colgate merged with Palmolive. This bar was made after the merger.
These were sold with coupons that you could trade in for various merchandise such as towels.
In the third photo you can see the Vaseline glass Colgate soap dish which is shaped like a washboard. This soap was made for use with a washboard so that explains that.
