Extract green areas, parks, land use

Yes you can. You will need to give a more detailed question to get a proper answer though.

One option is to download a region, then work with that file to extract what you need. Geofabrik for example has a wide variety of regions and download formats.

If you want just a small area or on demand live data, you could use the Overpass API. There's a very userfriendly interface available. Check this Overpass-turbo example. Data can be extracted in several formats through the site.

You'll need to define exactly what is and what isn't green areas, parks, squares, etc. The wiki will be of great use there. Squares are a bit difficult, as these are hard to define. You could try with pedestrian streets mapped as a closed way.