The CSV (character separated values) file format for chromatography coupled with mass spectrometric detectors is structured in the following way:

RT(milliseconds);RT(minutes) - NOT USED BY IMPORT;RI;15;16;17;18;19;...
5190;0.0865;0.0;170.0;735.0;1378.0;7122.0;0.0;...

Loaded into a spreadshirt with separator ; it results in:

The first column RT(milliseconds) contains the retention time in milliseconds.

The second column RT(minutes) - NOT USED BY IMPORT contains the retention time in minutes. The value will not be used for imports. It's just to support humans, cause who knows without calculation that 5190 ms are 0.0865 minutes.

The third column RI contains the retention index.

The following columns are the m/z matrix. It starts with the lowest m/z value, e.g. m/z 15 or m/z 32 or ... it depends on the data set. The first row marks the m/z values. Each following row represents a scan. Hence, it contains the intensity of the corresponding m/z value. The intensity is 0 if there's no such m/z value.