When you are "open to" a suggestion, it means that you might consider it. You don't mind thinking about it, and you might be convinced to follow the suggestion.
For example, if you're trying to pick a restaurant to eat at, and a friend asks you whether you like Ethiopian food, you might say:
I don't know. I've never had it. But I'm open to trying it.
You can ask someone whether they're open to a particular idea or suggestion:
Would you be open to the idea of selling your business if someone made a strong offer?
The opposite of "open to" is "not open to":
It seemed like she wasn't open to any other suggestions.