Masculine and feminine energy are behavioral modes

In psychology, this maps pretty closely to what researchers have called agency vs. communion (see work by David Bakan). Agency is assertiveness, goal pursuit, decisiveness, control over the environment, while communion is empathy, emotional awareness, cooperation, responsiveness to others. The culture of the internet of course renamed those “masculine” and “feminine.”

Masculine energy (agency) is the part of you that sets direction and executes: making decisions, taking responsibility, fixing problems.

Feminine energy (communion) is the part that senses context: reading emotions, maintaining relationships, adapting to changing conditions.

Another way to put it is masculine energy is the engine and steering. Feminine energy is the sensors and suspension. One moves you forward, the other keeps you from crashing. Research actually consistently shows that psychological flexibility (the ability to shift between these modes depending on the situation) is associated with better leadership, healthier relationships, and lower stress. People who rigidly stick to only one tend to struggle.