No worries, i think your English is quite good!
Hay is vital in their diet, but more for digestion and to wear their teeth down since their teeth don’t stop growing. He could be nipping out of annoyance, like when you got on the floor with him, and when he bit at the broom. It sounds like he see’s that area as his territory and his nipping/biting and grunting/growling is territorial. Nipping/nibbling is perfectly normal with bunnies, its part of their communication. He is probably just saying, “Hey, i don’t want you here.” when he nips when you mess with things on the floor or enter.
Bunnies are very very territorial. Especially when they aren’t fixed, so its good that he is. But, for at least a month after a bunny has been neutered/spayed, their hormones are still draining. It takes at least a month, sometimes more, for their hormones to leave their system completely. Bunnies will always be territorial, but they aren’t as territorial after being fixed.
You can try to neutralize the area, by putting together a white vinegar and water solution and spraying the floors with that. After spraying, wipe it up and spray with plain water and then wipe that up. It helps to remove any scents and helps it become a neutral area, where he’s less likely to be territorial. 