There can be easements for several reasons, utilities are a few of them. It looks like there is a pipeline easement on the right side with a minimum set back to any structure. The rear easement appears to be for drainage as the drain basin suggests. Without elevations or contours noted, that would be my best guess. Most easements allow you to use the yard space and sometimes have small portable sheds. Any permanent structures are off limits. If the easement is for utility access (perhaps getting to the drain basin), then any yard play sets, gardens, landscaping, etc. may be moved or removed at your expense.