Final answer:
The expression representing the product of a variable l and 59 is written as 59l, which indicates multiplication and maintains the dimension L of the variable l.
Step-by-step explanation:
The expression that means the product of a variable l and the number 59 is simply written as 59l or l multiplied by 59. This is a basic algebraic expression indicating multiplication between a variable and a constant. In the context of dimensions, the product of a dimensionless constant (which is what the number 59 is considered as) and a variable with dimension L (length) is still dimension L, because multiplying a number by a dimensional quantity does not change the dimension of the quantity.