Bonjour Wiem ! You can try clicking on the column border itself and dragging left and right to adjust the column width. You can also press CTRL + Left or CTRL + Right. However, note that while you can adjust the width of headers independently, columns broken down by a dimension cannot have independent widths.
To those posting:
It is translated to: Change the row or column to fit the text in the table
you can change the width of columns by dragging them like you would in Excel
Unfortunately the functionality you are asking about is not in tableau... yet. I recommend upvoting this: https://community.tableau.com/ideas/1362