If the idea tickles your fancy and you want to look into voice work more, please consider checking out LibriVox. It's a website with tons of open domain audiobooks voiced by volunteers. Their volunteer section has a lot of good info.
I don't volunteer to read, but I greatly appreciate the work they do. They don't accept donations anymore, but request people route to the Internet Archive. All green flags in my book.
My guess is they meant you sound like a "default character" voice (I feel like that sounds negative but I don't mean it that way). Like if you were to be the narrator for a menu, a random character, the main character's friend etc, your voice wouldn't be distracting or feel out of place. Maybe the voice of an audiobook or online language course or something?