A lot of space refers to a large or ample amount of area, room or freedom. It can be used in various contexts such as physical space, mental space, or time. For example, someone might say they have a lot of space in their house if it is spacious and has plenty of rooms for storage or living areas. Similarly, one could also say that they have a lot of mental space to think about something or make decisions. In other words, the phrase "lot of space" means there is an abundance or copious amount of something available.