A head for figures?

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In 'figure' article in a dicitonary, 'a head for figures' come up two times and

6 figures [plural] British English :the activity of adding, multiplying etc numbers [= arithmetic]

• a natural ability with figures

8 a person in a painting or a model of a person:

• the figure in the background

• A Head for Figures

I want to know what 'a head for figures' means?

It seems like the meaning of the expression can be 'be good at arithmetic' in meaning six. But in meaning eight I cannot figure out what the 'a head for figures' refers to. Does it still mean 'be good at arithmetic'?

Thanks in advance.