When playing in matches and tournaments you will be asked what padel skill level you have. You have to be honest with yourself and make your best judgment. Putting yourself in a lower level means playing with slower players and you will not enjoy yourself. On the other hand, placing yourself in a group of higher skilled players means that you will be a nuisance to other players and potentially ruin a match for another three players.
Slam Club in Barcelona provides a very handy padel skill level qualification PDF that explains the padel skill levels. Apart from being useful for joining tournaments and matches, it is also useful to keep these levels in mind when setting targets for yourself. You can, for example, set a target to try and advance one level every 6 months, and you will know exactly when you get there based on the information provided in this PDF.
Note that the PDF is in Spanish, so use Google Translate to change it to your language if necessary. If there is enough demand for it, I can translate it to English, just leave a comment below if you need that.
Another useful level guide is this one provided by the Guia Padel book, which is probably the best book about padel there is at the moment. Again, it’s in Spanish. I found it even easier than the other guide, and qualified myself as 3.5-4. There’s definitely a lot of progress to be made, but that’s part of the attraction of this sport!