Welcome to the forums, Tina!
The Budapest Card comes in two flavors, one is valid for 48 hours (HUF 6,300) and the other is valid for 72 hours (HUF 7,500). Both cards include unlimited travel on public transportation and discounts at participating museums, restaurants and spas.
It can save you money compared to buying all the admission fees individually. Whether you are getting good value all depends on how many deals offered by the Budapest Card you can actually take advantage of. It’s great that you’ll be getting a discount, but if most of the attractions don’t interest you, or the given time frame is too short, you’re not getting much value. So, it’s really up to the time and your interests.
There is also additional info in our Getting Around Budapest section.
Let me know if you had any other questions,