The recommended word count of a bio is 160 - 250 words. What you say could and should tell others' a little about your blog. It might say something about you too - on a professional level.
The balance between being informative but personable is something you probably won't get right first time.
If you want or need to use more than 250 words, consider using a hyperlink so those who want to read more can.
Here's a useful article for writing a professional social media bio:
and one pitched at artists too:
|Fine Art tips - Lori McNee|