When I came to Lebanon eight years ago, I didn’t speak Arabic. I took some classes but what really helped me learning the language and culture was interacting with the locals. If you wander around Achrafieh (and I’m sure other parts of Beirut as well, I’m only writing about Achrafieh because I live here and I walk around a lot), whether it is on the small streets around Sassine square or Saint Nicola’s Cathedral, you will spot a lot of elderly locals. They will be just sitting on plastic chairs in front of their buildings or shops, playing cards or backgammon and sipping “ahwe” (an Arabic word for coffee). You will notice how they are eager to talk to you, to just say hi and ask you how you are and inviting you to have a coffee with them.
If you start passing by the same spots regularly you will see how they recognize you and wave at you from a distance. A truly heartwarming and unique feeling that makes you feel like you are in a small village where everybody knows you, despite being a stranger in the capital of Lebanon.
I strongly encourage you to take an hour or two to walk around and interact with the locals, have “ahwe” with them, let their kindness overwhelm you. The fact that you don’t speak Arabic won’t be a problem: they will try even harder to understand you and use whatever foreign vocabulary they might know.