This is the 6564th most frequent Russian word.
energy
The capacity for activity or the power to do work.
Here, 'energy' refers to a physical concept, namely the energy derived from sunlight, which is a natural resource.
Энергия солнечного света используется для производства электричества.
The energy of sunlight is used to generate electricity.
In this sentence, 'energy' describes a person's vitality or stamina to perform tasks.
У нее сегодня полно энергии, она успевает сделать всё.
She has plenty of energy today; she manages to do everything.
The use of 'energy' here relates to the metaphorical or emotional power conveyed through creative expression.