Muscular Endurance training is a type of weight training that trains the endurance pathways of the muscle. What this means in basic terms – this type of training allows you to do a lot of reps with a light/moderate weight. Think of the guy you knew in high school that could do 100 pushups in one set. That guy had a lot of muscular endurance. Similar to other specific training methods, getting great with muscular endurance takes a lot of energy and time, leading to less overall maximal strength and sometimes even hypertrophy. If you can recall, specializing in one training modality usually lessens the progress of other modalities.
A lot of people love combining calisthenics with muscular endurance training. This can be great because your body weight probably doesn’t fluctuate too much if you have your diet locked down. Knowing your bodyweight is always similar, you can improve your push ups, pull ups, and pistol squats with the proper training. You don’t only have to use your bodyweight for muscular endurance, however. You can use weights, resistance, etc. just as you would for other training types.