If you want a single figure to quote, then normally that is the download speed. For most people, the download is the limiting factor except when you are sending emails or hosting a website. Even when the download speed is 10 times faster than the upload speed, for general browsing, watching movies and receiving emails, you will hit the limit on download before the upload limit. There will be a small amount of upload traffic as you will be sending requests for information to the Internet, and you will be acknowledging the receipt of data packets you are receiving. (By you, I mean your computer.)
Now, the screen shot of your WiFi connection shows 54 Mbps (Mbps is Megabits/second while mbps is millibits/second, which is a billion times slower - yes 10 to the power 9 times slower). The 54 Mbps refers to the speed of the wireless interface between your router and your computer. Similarly, most Ethernet connections will work at 100 Mbps (although some do 1000 and some only 10 Mbps). WiFi does NOT come from your ISP, it is purely on your side of the router. If you have a 200 Mbps ISP (Internet) connection, but your computer is connected by Ethernet to the router, you are not likely to see speedtest.net report much over 90 Mbps. That's 100 Mbps, but there are some protocol overheads that can drop the speed below the raw Ethernet speed. Speedtest.net will be limited to the speed of the slowest interface even if the ISP connection is much faster. For WiFi, you might only get around 25 Mbps in Speedtest as WiFi uses a two way alternate connection and can suffer from packet collisions, while Ethernet is two way simultaneous and normally has no collisions when only one device is active.
Unlike the speed you see reported in the WiFi status screen, Speedtest actually measures the best average speed it can achieve end to end between your computer and a remote server, while the WiFi status reports the instantaneous speed just between your computer and your router.
I hope this clarifies the position.