If you are a novice, you should learn a method slowly. When skating is not fast, you can use tail glue (that is, the plastic block you said). The method is to raise the palm of your right hand and let your feet follow the ground. The braking effect of tail glue depends on the quality of your shoes, but it is generally not the main one, and it can also play a protective role (to prevent falling backwards).
At first, you may not be able to do the former method. You can try to understand the braking skills by using the principle of "turning" first.
When taxiing, turning sharply can also achieve the braking effect. Then you need to master the skills of turning first. Changing the direction of the pulley between lifting the foot and landing is the basic method of turning. After proficiency, you can gradually speed up and increase the turning angle before turning, until you can make one foot as the center of gravity and draw an arc in front of the other foot (just like sweeping the legs in martial arts novels), which is not far from success!