Sometimes you might be required to actually count your freight as it is loaded into the truck. When this happens, sometimes the fork lift operator will not actually load in a way that you can count. Stop him and address the issue. Just tell him/her that he/she needs to slow down and so you can count.
When you don't have to count which is most times at the average trucking job, sign your Bill of Ladens (paperwork) and write SLC after signing.
SLC stands for Shipper Load and Count. That means that the shippers was responsible for counting the freight.
Don't worry though. Most of the time, you won't need to load or unload freight. If you have to count, you will usually just have a sheet of paper and pen and multiply the number of pieces per row x the number of rows on the pallet.
In this video, I am actually specializing in furniture. When we deliver we count what the pieces that we unload. If you happen to haul LTL freight with multiple stops you will have to count as well.