Theme Integration

Hi,
I’m wondering, is there any good/detailed tutorial about how to fully integrating polylang with theme?

I know there are documentation for it https://polylang.wordpress.com/documentation/documentation-for-developers/general/, but I just dont get how to use the pll__ or pll_e in the theme along with standard WordPress translation function.

https://ww.wp.xz.cn/plugins/polylang/