This could be something as simple as spacing. The example code you specified shows a space between the first quote and the /Users. Remove that space. If it doesn't work, try this to get the exact path:
Navigate in Finder to the file you want to import and click once on it, then hit Command+i to open the Get Info window.
Find the WHERE line in the Get Info window, and click and drag after the colon to select the path, then hit Command+C to copy the full path to the clipboard.
In your code, after read_excel( enter two single quotes next to each other with no spaces. Click after the first one, and then Command+V to paste the path in between them.
Move to after the ending quote and place your closing parenthesis. Try running you code again.