This is my first oscilloscope and i don't know if this is normal.
Normally oscilloscope should display 50/60 Hz sine wave in such condition.
This is electromagnetic radiation from AC power supply network in your home.
But the sine wave on your screen is distorted with a lot of impulse noise.
The reason for that are digital circuits and switching power supply modules near to your oscilloscope.
Primarily it's oscilloscope switching power supply and display.
The display is emitting electromagnetic radiation at high frequency (about 62.5 MHz for Siglent model).
The switching power supply is emitting electromagnetic radiation at low frequency range (1 kHz - 1 MHz), but it has a square waveform and it means that it has a lot of harmonics.