Word & Fonts
To be clear you are not installing the font into Word. You install a font onto your computer, then programs such as Word will show the font as a choice.
If properly installed on your computer, then you can see Helvetica as a choice in your Word menu and that installed font can also be used in other computer applications that have the capability to specify fonts.
Lots of resources exist to learn about your computer operating system and how to add and install fonts. If you have gotten this far, try the help menu on your computer, use the Microsoft, Apple, Linux website or use google to search for how to install a font.
On a graphic design computer graphics work-station installed fonts are carefully organized and managed beyond the out of the box computer typical setup. Many advertising agency, graphic design firms and studios work have complex needs some work with a computer support business to set up and maintain the computer graphics work-station. With only a few full typeface families, having a couple hundred fonts on a typical computer the modern OS's are engineered to handle these numbers of fonts, and programs such as Word can also show the added font choices in its font menu.
Purchase a new computer and it will likely have its operating system installed. That operating system will have some fonts too. The new computer might include some Helvetica fonts from the Helvetica typeface family. In purchase of a new computer you agree to the licensing of the computer operating system and the licensing of any applications, fonts or typeface families when you turn on that computer and go through the set up. During the the set steps, included is end user licensing agreements or EULA. These EULA contain the information about how you can use the applications and fonts on the computer hardware you paid for. You do not own any of the computers OS, applications or fonts, you have licensed the use of these tools and resources, this licensing is detailed in each EULA.
Yes you can purchase (license for use) the Helvetica Complete Family Pack, then install this on your computer. If you choose to add Helvetica fonts or other fonts to your computer look for the Open Type version of Helvetica to purchase (license). If you don’t require all 37 styles in the Helvetica Complete Family Pack, then you can purchase just a few of the Helvetica weights to start out. Good basic choice is Helvetica Roman, Helvetica Oblique, Helvetica Bold, Helvetica Bold Oblique.
Lots of online resources exist to learn about your computer operating system and how to add and install fonts. A number of good places exist to purchase fonts and to obtain programs to manage large font collections too.
These are some url's that have font information for you to learn more.
Reputable places to license Open Type fonts used for commercial use.
Reputable places with software to organize and maintain a font library.
Reputable places with information about OpenType fonts.