I speak to my friend in English every week.

[dwni1]

For example, I want to tell somebody that we use english to comunicate.
Are the sentences okay?
I speak to my friend in English every week.
I speak to my friend about politics in English every week.

 

[Tarheel]

They're OK.

 

[tedmc]

"We/I use English (capitalized) to communicate" is fine. "Communicate" is both speaking and writing.

 

[emsr2d2]

For example, I want to tell somebody that we a friend and I use English to communicate. Are the sentences okay?

1. I speak to my friend in English every week.
2. I speak to my friend about politics in English every week.

Note my changes above, and note that I have changed your thread title.