Translation:There are many flowers blooming in this park.
I read that the ～ている form doesn't always mean " are ~ing." For verbs that are a change in state, the ～ている form means that the change has occurred, and that the current state is after the completion of the action. So I think this sentence actually means something like "there are flowers in the park" or "the flowers have bloomed in the park." This seems like splitting hairs here, but for verbs like "to become married," or "to become fat/skinny," It makes a significant difference in how the sentence is interpreted.