Excel the sum of my cells is 0

Thank you very much for your answers! However, I wanted to clarify that I did not enter a space; I really used the thousands separator in the format to mark the space.
By the way, I remembered a detail: it's a document I downloaded from Google Docs Excel, so the problem might come from there?

You can:
either delete the stubborn column
or send us your file so that we can see where you made an error

 1) Go to https://www.cjoint.com/ 
 2) Click on [Browse] to select your file (max 15 MB)
 3) Scroll down to click on the blue button [Create Cjoint link] 
 4) After a few seconds, the second page will appear, with the link in bold; right-click on it and choose "Copy link"
 5) Go back to your discussion on CCM, and in your message, click "Paste".
=>See the guide https://www.commentcamarche.net/faq/29493-utiliser-cjoint-pour-heberger-des-fichiers 

--
Retirement is great! Especially in the Caribbean... :-)
Raymond (INSA, AFPA, CF/R)

As I expected, your column B only contains text!
As soon as you have fun typing a space between two numbers, you create an alphabetical character and you get text.
In B2, you should not enter 58 490 but 58490 and choose a number format with a thousands separator...
My friend's solution ccm81 will therefore not be suitable in your case...
It's nice, retirement! Especially in the West Indies... :-)
Raymond (INSA, AFPA, CF/R)