Simply speaking from experience.
People used it to write business applications. Like Microsoft Access, or Visual Basic.
It started as a competitor to dBase II/III called FoxBase, and then Microsoft bought it.
Since then everything became much more complex - networking, security, GUIs, web development, deployment, etc.
Successor - Visual FoxPro: https://en.wikipedia.org/wiki/Visual_FoxPro
Not a single language nowadays can do that
A primary bit of tech that came out of the purchase was the core DB engine. They reworked this into what became the Jet engine. The Jet engine was the core of Access.
Access was in many ways a next generation of FoxPro. They both went after the same niche of desktop and file server DB applications. But FoxPro carried the legacy of its dBase roots, FoxBase was basically “better dBase”, but had to appeal to and be familiar to dBase developers.
Access had no heritage like that to hold it back, and was a better citizen in the VB/Office/OLE/COM world. It was also more SQL first even though it kept things like DBF files as first class citizens.