Answer:
When we talk about linear patterns, we refer to those events where events are related with a linear proportion, that is, if one magnitude increases, the other one will to, or if one magnitude increases the other would decrease, and this behaviour with a linear function which is represented as a line.
So, one example of linear model would be speed, which relates distances and time in a linear behaviour, which function is

So, if one ball has a speed of 3 meters per second, the function would be

Where
represents the independent variable (horizontal axis) because it represents time, and
is distance, which is a dependent variable.
On the other hand, a non linear model could be population growth, which is an exponential beahaviour. It's not represented with a linear function, that's why is not linear.
An example of a function that represents population growth is

Where
is time (horizontal axis),
is growth rate,
is the initial population and
is the population after
time.
A specific example is

At last, each function graph is attached, there you could see a lot better, the linear and non-linear behaviour.