Your question is not specific enough. It depends what you want to measure. There are different aspects to measure. Simple things like voltage and current are pretty easy to measure with a multimeter.
How hard is measuring a person? Measuring height and weight are easy. Measuring intelligence or health is much more difficult.
I assume that you asking for measuring either Voltage or Current.
The easiest way to meausre these parameters, is by using a device called 'Multimeter'. It have two probes and many different modes.
Like for measuring voltage, set it on voltage mode and connect those probes to Live and neutral wire of electricity. Like below you can measure both DC and AC voltage:
Same for measuring current set it on current mode and connect those probes to Live and neutral wire of electricity. You can measure only DC current using shown multimeter.
Image source: https://circuitdigest.com/article/how-to-use-a-digital-multimeter
You can also use mutimeter for measuring resistor value and as a continuity tester.