The same provision states that council "terms need not be of the same length." How would that work?

A few cities elect some council members to four-year terms and other members – actually, usually only one member – to two-year terms. Take, for example, a council with five members. Every two years, three members are elected. Those two receiving the most votes get four-year terms, while the person finishing third gets a two-year term. As a result, a majority of the council – three members – is elected every two years. It might be noted that this system only works if the council members are elected at-large.

In addition, it would be possible for a city to designate certain seats on the council as two-year term seats and other seats as four-year terms seats, although no city currently has such a structure.