Imagine a bunch of little houses that all have different functions. Some are for sleeping, some are for cooking, some are for playing, and so on. Now imagine that each house has little doors that only open when certain things happen. For example, the door to the sleeping house only opens when it's nighttime and you're feeling sleepy.
This is a bit like a compartmental neuron model. A neuron is like a little house that has different functions. For example, one part of the neuron might be responsible for receiving signals from other neurons, while another part might be responsible for sending signals to other neurons. In a compartmental neuron model, we divide up the neuron into these different parts, or compartments.
Just like the doors in the little houses, each compartment in the neuron has little "gates" or "channels" that only open when certain things happen. For example, one channel might only open when the neuron receives a certain type of signal, while another channel might only open when the neuron is actively sending a signal to another neuron.
By modeling neurons in this way, we can more closely study how they work and how different factors (like the strength of signals or the types of channels present) can affect their behavior. ELI5: Compartmental neuron models are like little houses with different functions and gates that only open under certain conditions. By studying them this way, we can learn more about how neurons work.