There different types of wording that tells us that we have a rate of change.
For example, when talking about speed, or in general, when talking about any measure per unit of time (meters per second, gallons per minute, miles per hour) all these are rates of change.
Other example, not as common as the first one, is when the statement refers to a slope, which is in other words, a rate of change.
Similar to the first one, when the statement talks about amounts and/or growth over time, for example: On the first day the plant was 10 cm high, on the second day it was 15 cm high, on the fifth day...