Something that characterizes formulas in R is the tilde operator ~. With this operator, you can actually say: "capture the meaning of this code, without evaluating it right away”. That also explains why you can think of a formula in R as a "quoting" operator.
But what does a formula exactly look like? Take a closer look at the following line of code:
# A formula
c <- y ~ x
d <- y ~ x + b
# Double check the class of `c`
The variable on the left-hand side of a tilde (~) is called the "dependent variable", while the variables on the right-hand side are called the "independent variables" and are joined by plus signs +.