What does {variable} means for on regex?

what does it mean the {c} on the following code?
I know curly braces can specify the number of repetition of the previous char, but what do they mean when we have a variable inside of the them

r = 0
jobMatchingScore = (l, c) => l.map(e =>
    r += !!e.match(`(^|, )${c}$`)
) | r

the link of the challenge on codesignal :point_down:

1 Like

c is probably a number.

This is a template literal. It is the ${} that is the important part.