An attribution statement is used to provide credit to the original creator; its purpose is similar to a citation. Best practice says that the statement should include the title of the work, name of the creator, and license type (with links to each). When using text from another open educational resource, be clear in your attribution statement what section of your course, textbook, etc. contains this information.
All CC licenses require users to attribute the creator of licensed material, unless the creator has waived that requirement, not supplied a name, or asked that their name be removed.
Additionally, when you are using a work that is an adaptation of one or more pre-existing works, you may need to give credit to the creator(s) of the pre-existing work(s), in addition to giving credit to the creator of the adaptation.
Adapted from: "Citation vs. Attribution" in Self-Publishing Guide by Lauri M. Aesoph, licensed under a Creative Commons Attribution 4.0 International License, and "Attribution" in Creative Commons FAQ, licensed under a Creative Commons 4.0 International License.