Could someone help me doing some SW exercises
There are two answers.
1.) if you know software how it works then you should do only modelling practices of part and assemblies. there is lot of content available on google as well as you can do modelling of live things like your Pen, mobile, laptop, water bottle ,kitchen furniture etc.
2.) If you do not know software or you are at beginner level, then you should start with sketch module, it is most imp module practice as much as you can. draw different type of sketches, you need to give max time to sketch.
3.) for part modelling, you need to model mechanical block using without iso view so you can enhance your 3D visualization. at least make 5 block per day then go to the assembly.
4.) drafting as important as sketch module practice as much as possible.