What does Proportional by Equity mean?

When copying a signal, "Proportional by equity" adjusts the size of your trade relative to your account size so it mirrors the size of the signal's trade in proportion to their account size. This means you are taking a similar risk to the signal you're copying. Buying £5,000 of CAP40 is much more risky for an account with a balance of £5,500 than for one with £100,000!