Purchase AWS Saving Plans advice

We have a Linux instance that we need to run for at least 1 year. We are currently using the On-Demand pricing model, but we are interested in switching to a Savings Plan one. I want to know more about these plans, and help me choose the right one for our needs? I am also interested in learning more about the sign-up process.

• EC2 instance type: m5.large

Thank you for your time