How can I hide this ugly gas meter?

see if you can find some sort of pretty garden statue or gazing ball, easy to move when the meter reader is coming, and when you need to trim the lawn

You can put a nice planters crate over the front of it and plant flowers around. It can then be picked up or moved when the gas company needs access

Hosta there are many kinds of hosta and they come back year after year

Put a fake tree in front of it............

Create a privacy screen out of pallet wood or old shutters, connecting two of them in the center with hinges so it can fold like a book; you can make as tall or short as you want and any color. Even put planters or plant hooks on it

You might want to talk to your gas company before you do anything expensive or permanent. My husband works for a utility company and he's always telling me how if they need access to a meter or box, because of the law and easements, they have a legal right to cut down shrubs or remove structures that impede access. His division goes out of their way to avoid damaging anything, but, from the stories he's told me, not all utilities are all that careful. He recently told me about an electric company removing expensive shrubs with a chain saw when they didn't have access to their enclosure. Remember too, to put in a One call also known as a 411 call before doing any digging anywhere near your gas line or meter. A gas leak is dangerous.

Plant up a large container with a tall perennial gras then plant all around with flowers.

Maybe the area with the potted plant and the meter can be planted with a hardy ground cover like pachysandra. It won't get very high, but it will at least take attention away from the meter. Maybe you can get a fairly inexpensive wall-mount holder to hang your house from, as well. Then you can extend the pachysandra in that area also. Have fun!

I'd plant some ornamental grass in a variety of heights & colors along the front of the block wall. Add some low colorful flowers to the edge of the border. This wouldn't completely cover the meter, but eyes would take in the entire picture, instead of zeroing in on the meter.

I agree with Cynthia. Check and see what alternatives the gas company will allow. I got tired of seeing the neighbors meter and put a pot of ferns that I dug up by it. Hopefully when they get bigger they will cover it, but is also moveable in case they need to work on the meter or physically read it. Most all gas and electric meters are read electronically while they are driving down the street in my town, but I know they have to read it physically on occasion to make sure the readings are accurate. My neighbor gave me permission to do what ever I want on our side of her house since the houses are so close together, Maybe eight feet from her house to our driveway. I care for her lilac tree and prune the one shrub on the side of the house. This allows me to put up shepherd hooks and my strawberries there and care for the ferns and hostas next to the fence between her house and our garage.

Make a lidded box that has a slanted top and an obvious handle and is hinged to lift for the readings.