You can think of a blog as a resource or a place to tell stories (among other things). If your nonprofit has great stories to tell about volunteers or clients, this is a way to showcase them online. You are publicly recognizing their great work and sharing your successes with donors.
For me, I use this blog as a resource. I was often getting the same questions from people about technology tools and social media. This blog is a great place to refer people with questions about these topics.
If you think either of those directions would work for you, you may want to talk with your team about getting started. However, if you are having trouble coming up with ideas, don’t stress about it. The timing may not be right for you or a blog may not be the best direction at all. Either option is fine. No one can do everything.