A balance would be used to measure the weight, which in turn effectively measures the mass (more or less). Imagine that we have a brick that we know is 1 pound. If we have an object that needs 5 bricks on one side to balance it out, then we know the object is 5 pounds.
The beaker is used to measure the volume. It's basically a measuring cup that you would find in the kitchen.
To get the density, you divide the mass over volume.
For example, if you have a material that has a mass of 100 grams and it's volume is 20 cm^3, then its density is 100/20 = 5 grams per cm^3.
