A conversion is expressed by the achievement of a main objective, itself defined as the loading of a page previously declared as an objective from your interfaces.
Conversions (loads): number of times goal pages have been loaded within the analysis period.
Conversions (visits): number of visits during which at least one main goal was achieved within the analysis period.
Example: within the same visit, a user loads 3 times a goal page. Here's the output: 3 Conversions (loads) and 1 Conversion (visits).