In magic, planeswalkers are not considered creatures, this is true. But they can be made creatures by other effects. Most specifically the Gideon planeswalkers all have an ability that "animates" them, makes them into creatures, from the original Gideon Jura with his ability:
0: Until end of turn, Gideon Jura becomes a 6/6 Human Soldier creature that's still a planeswalker. Prevent all damage that would be dealt to him this turn.
To the most recent, Gideon of the Trials with his ability:
0: Until end of turn, Gideon of the Trials becomes a 4/4 Human Soldier creature with indestructible that's still a planeswalker. Prevent all damage that would be dealt to him this turn.
While these are active, Gideon can attack like any other creature, following the normal creature rules, untapped and not summoning sick etc. The abilities only last for the turn, so they don't usually allow Gideon to block, unless there is a way to activate them on opponents turns, like through the emblem of Teferi, Temporal Archmage.
There are other ways to animate planeswalkers, usually that involves making them some other card type that can be easily made a creature. The common way to do this is with a card called Mycosynth Lattice, which makes everything, planeswalkers included, into an artifact, and there are many cards that can turn artifacts into creatures, like March of the Machines or Animate Artifact, even some planewsalkers themselves, like Tezzeret, Agent of Bolas could turn themselves into a creature.