To open a CSV file and see its rows and columns, import it into a spreadsheet app such as Microsoft Excel, Apple Numbers, or Google Sheets. For a quick look at the raw text, open it in a text editor instead.
In a spreadsheet app, choose the CSV file to import and check the preview before confirming. Make sure the first row is treated as column headers if it contains names such as name,email,city. If every row appears in one column, choose the file's delimiter, such as a semicolon instead of a comma. If accented characters look wrong, check the CSV encoding.
You can try this with a sample CSV file before importing your own data.
If you need to clean or combine the rows after opening the file, use a CSV editor. For a file too large for your spreadsheet app, choose a tool that supports its row count and available memory.