Arduino Uno is a ATmega328P based microcontroller board. It has 14 digital input/output pins , 6 analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP header and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.
To get started check our below link
You can check the below video tutorial for hands-on start using Arduino Uno
For Details specification check the below Link