What you can ride with the A license
The A license lets you ride any motorcycle, without the 35 kW cap that applies to A2. That is why it appears in searches such as "A license Spain" and "what motorcycle can I ride with A".
If you already hold A2 and want access to larger or more powerful bikes, A is the category that removes that limit. Even so, the process is different from getting A1 or A2, so the path needs to be planned correctly.
Requirements to move from A2 to A
The usual route requires a minimum age of 20 and at least two years of prior A2 holding time. That combination is the main constraint for anyone planning the upgrade in Spain.
In practice, the key question is not only your age but whether you already meet the A2 seniority requirement. It is worth checking that before comparing schools, prices, or course dates.