How to calculate signal energy?

Question

Signal processing

I divide the entire signal (two vectors: timestamp and sensor reading) into intervals. Then I need to calculate for each interval its characteristics: mean, standard deviation, variance, energy, kurtosis, skewness, minimum, maximum.
If with all the rest everything is more or less clear, then I can’t figure out how to calculate energy.
Can someone show a specific example? Is this done somehow through the Fourier transform?