To find out the speed of your wireless Wi-Fi connection on a Mac, follow these steps:
Click the Wi-Fi icon in the menu bar at the top of the screen.
Hold the Option key, and the Wi-Fi icon will change to display additional information, including the current connection speed.
The connection speed is displayed in megabits per second (Mbps), and it represents the maximum data transfer rate that your Wi-Fi connection is capable of achieving.
Alternatively, you can use the airport command in the Terminal to see the connection speed. Open the Terminal (located in the Utilities folder in the Applications folder) and enter the following command:
/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I
This will show information about your current Wi-Fi connection, including the connection speed. The speed is displayed in the agrCtlRSSI field, which stands for "average control channel receive signal strength indicator." A higher number indicates a faster connection speed.
Keep in mind that the actual data transfer rate that you experience may be lower than the maximum connection speed, due to factors such as interference and distance from the router.