I have included a picture. My applications folder is on the dock and when I click on it the applications come up but the icon size is too big, is there anyway to make these icons a lot smaller? any help is much appreciated.
To change the size on the Applications Dock menu in Grid view click the Applications Dock Tile and then press command- to make the menu and icons smaller or command+ to make the menu and icons larger.
I have tested this under OS X Mountain Lion 10.8.5, OS X El Capitan 10.11.6 and macOS Sierra 10.12.
The image below is from OS X El Capitan 10.11.6 taken on a Thunderbolt Display at 2560 x 1440 and of three separate screen shots that were cropped from the lower right corner to the size necessary to show the size of each grid menu and its size changed and layered to reduce the size of posting 3 individual images. Nothing has been retouched, just cropped and layered to contrast between a large menu in the back, the default size menu on this Display in the middle and a smaller sized menu up front. Calculator.app was used to show scale and as you can plainly see the size of the icons changes with the size of the grid menu.
There is no way to change the size of the icons in the grid itself (the keyboard shortcut that worked in macOS Lion no longer does), but you can change it to list view by right-clicking on the folder icon and selecting List. This will result in a list similar to a Finder view, with much smaller icons.
Edit: After further testing, the commands that I said no longer worked from Lion actually do work, at least in my testing in macOS El Capitan 10.11.6. They did not work initially, and when they finally did start working it took several seconds for anything to happen, though now they seem to be working ok.
They are: Command-+ to make them larger, and Command-- to shrink them.