A record album consists of one continuous sound groove. The groove carries the needle from the beginning to the end of the sound recording.  All along the edges of the sound groove is a series of " hills and valleys" or notches carved into the side of the groove. As the needle scrapes alongside of these hills and valleys the friction causes the stylus to vibrate (just like scratching your fingernails over any surface). A rough surface makes one sound ... a smooth surface makes another sound). This is how the sound is generated through the vibration of the stylus. The sound groove contains hills and valleys on both sides (see diagram). The ones on the left side of the groove set up vibrations in the left side of the stylus. The ones on the right side of the groove set up vibrations in the right side of the stylus. This accounts for a different sound being available for the left and right side of the stereo. 

The vibrations that are caused in the stylus are transferred through the tone arm and into the amplifier. Once amplified, the speakers can reproduce the sounds as recognizable words and/or music.