Everything in the dream refers to the things in the dreamer's real life.
An important thing in the dream is a snake. Generally speaking, snakes are disgusting things.
It shows that the landlord has recently encountered difficulties or crises, and a very powerful person (the dream friend's father) was the first to help the landlord break the crisis, and the landlord also made some efforts (the snake that got into the doorway was beaten back by the landlord).
The snake here may refer to the crisis in the landlord's life, or people who the landlord thinks hate or hinder the landlord. Dreams help you realize your wishes, and you destroy crises or enemies with the help of others.
But after all, the landlord stood behind the glass door, and you didn't face the crisis directly. I hope the landlord can be braver in real life and have the courage to face difficulties or enemies directly!
Riding a bike in the pool is actually the same. It can be considered that although the landlord has a sharp weapon (bicycle) to move forward, you are still trapped in the "swamp" (pool), and the resistance of the water makes it difficult for you to move forward smoothly.
Personal opinion, for reference only!