Resistors

A resistor is an electrical component used to create resistance in the flow of an electrical current. The amount of resistance a resistor has is measured in ohms. Resistors are important as supply too much voltage to a component you can completely destroy it. Resistors can be used to prevent this with just a little bit of math. 
To make calculations easier, I have linked 2 tools to help you calculate exactly what you need and what you have.
https://ohmslawcalculator.com/ohms-law-calculator
https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code
 
Read the color bands from left to right. The colors on the first 2 or 3 bands correspond to numbers from 0 to 9, which represent the significant digits of the resistor's ohmic value. The last band gives the multiplier. For example, a resistor with brown, green and green bands is rated at 15 mega-ohms (15,000,000 ohms). The code is as follows:[2]
Black: 0 significant digit, multiplier of 1
Brown: 1 significant digit, multiplier of 10
Red: 2 significant digit, multiplier of 100
Orange: 3 significant digit, multiplier of 1,000 (kilo)
Yellow: 4 significant digit, multiplier of 10,000 (10 kilo)
Green: 5 significant digit, multiplier of 100,000 (mega)
Blue: 6 significant digit, multiplier of 1,000,000 (10 mega)
Violet: 7 significant digit
Gray: 8 significant digit
White: 9 significant digit
Gold: multiplier of 1/10
Silver: multiplier of 1/100