How many milliliters of water has been dispensed if the initial buret reading was 0.47 mL and the final is 26.18 mL?

The displacement will be 25.71 mL.
You can determine the volume of an object by using a known volume of water and a graded cylinder (or a buret, like in your case).
When you place an object in water, the amount of water the object has displaced, which will correspond to the increase in volume, will represent the volume of the object.
In your case, the volume went from 0.47 mL to 26.18 mL, which means that the volume of the object will be
##V_”object” = 26.18 – 0.47 = color(green)(“25.71 mL”)##