To give you a rough estimate, an electric guitar played through a typical amplifier and speaker cabinet can reach a sound pressure level (SPL) of around 100 decibels (dB) at a distance of one meter. This is comparable to the noise level of a busy street or a lawnmower.
However, the loudness of an electric guitar can be significantly increased by using a more powerful amplifier or speaker cabinet, or by adding distortion pedals or other effects. Additionally, certain pickup configurations, such as humbuckers, tend to produce a louder sound than single-coil pickups.
It is important to note that excessive exposure to loud noise can damage your hearing, so it is always advisable to use hearing protection when playing an electric guitar at high volumes.