It implies a willingness to endure the unpleasant or challenging parts because they are inevitable and come with the good.
Here are some examples:
* "Being a parent is full of joy, but it also has its tough moments. You have to take the bitter with the sweet."
* "Life is a journey with its ups and downs. You can't expect to have only sunshine. You have to take the bitter with the sweet."
Essentially, it's a reminder that life is not always easy, but the good times are worth it even when you have to face the bad times.