The amount of videos you can make each month depends on the subscription tier you are subscribed to.
Each subscription tier includes a certain amount video creation time. For example, the Alpha plan includes 10 minutes of video creation time a month.
That video creation time can be divided between as many videos as you can make as long as videos are at minimum 5 seconds long.
For example, you could make twenty videos that are 30 seconds long a month on the Alpha plan, or you could make ten videos that are 60 seconds long a month.