"Freedom of wombs" means that women have the right to decide what happens to their bodies, especially when it comes to having babies. Just like you get to decide what toys you want to play with or what clothes you want to wear, women get to decide if they want to have a baby or not.
Sometimes, women use things like birth control to make sure they don't get pregnant, and that's okay because it's their body and they get to make that decision. Other times, women might find out they are pregnant but don't want to have the baby for different reasons. In some places, it's legal for women to have an abortion, which means doctors can help them end the pregnancy safely.
It's important for women to have this freedom because it helps them make the best choices for themselves and their own lives. And just like how you would want to be able to make your own choices, women want to be able to make choices about their bodies too.