The slope of the least squares line provides an estimate of the slope of the underlying regression model. A confidence interval describes its accuracy.
The first exercise asks for a 95% confidence interval for the slope, β1, based on the least squares slope and its standard error.
Harder exercise
The next exercise shows information about the least squares line in tabular form (as is often given by regression software) and asks for the upper and lower limits of the confidence interval. Variations ask for intervals at different confidence levels.
Repeat with a few different questions.