UML modeling application ionic

I have to create UML diagram for my upcoming project.
In fact my project is a business application app in which I will only develloped the front part and I will use the API of the backend part.
My question is how I can model a uml diagram of a front-end application
Someone help me please

I’m also having this issue can someone answer this.

UML is just the “language” of a diagram, what do you actually want to model?
If you want to define API endpoints of the backend, better use something like swagger to define the API.