What does, 'PHP or similar: Backend' and, 'CMS: Content Management' mean?

Answer 1

https://www.sololearn.com/post/10362/?ref=app
First question:
https://www.sololearn.com/Discuss/1733777/?ref=app

Second one:

https://www.sololearn.com/discuss/1122177/?ref=app
https://www.sololearn.com/discuss/1581665/?ref=app
https://www.sololearn.com/discuss/716304/?ref=app
https://www.sololearn.com/discuss/1451917/?ref=app
https://www.sololearn.com/discuss/2129724/?ref=app
https://www.sololearn.com/discuss/454458/?ref=app
https://www.sololearn.com/discuss/894096/?ref=app
https://www.sololearn.com/discuss/1940723/?ref=app