How to only show one pair of arrows, ando only one line of points?

Thank you.

The quickest is install the included Splide X, put the blocks and edit its options. Clone anything provided, or just edit.

Arrows and dot pagination are parts of an optionset.

All optionsets can be edited at Admin > Config > Media > Splide UI.
Be sure to enable Splide UI sub-module.

Arrows and dot pagination can be disabled there, or via Override main optionset.

If you want to change default values, avoid choosing Default for both Optionset options.

Default optionset must not be edited!

Create your own, or install Splide X for quick samples.

Thank you for your fast attention Gaus. By Splide X, you mean splide:^2.0? Because I already have it. But you are right I do not enable Splide UI. I will try to follow your tips.