Lens Recommendation for Birding Photography- Panasonic LUMIX G7???

I have a Panasonic LUMIX G7 camera, and I was wondering if anyone would have recommendations on what lens would be good for capturing birds? I have a somewhat limited budget, but I am willing to hear whatever recommendations you have. I don’t have much experience with photography, and I am getting into it slowly, so whatever information you can provide would be greatly helpful! Thank you in advance