My kids grandparents who live abroad would like to send money as a gift to my son who is 16 years old toward his college education. what are gift tax implications for me?

[DoninGA]

A gift received from an individual is not taxable nor is it reported on a tax return.

If the gift is from a foreign individual and the amount is over $100,000 then the gift has to be reported to the IRS using Form 3520.  This is an information form only - https://www.irs.gov/forms-pubs/about-form-3520

[Hal_Al]

Gift tax is not applicable to foreigners.

Even for U.S. citizens,  "Gift Tax" is somewhat of a misnomer.  Even though a gift tax return may be required, very few people ever actually pay federal gift tax. The purpose of the gift tax return is usually only to document a reduction in the allowable estate tax exemption.
See https://turbotax.intuit.com/tax-tools/tax-tips/Tax-Planning-and-Checklists/The-Gift-Tax-Made-Simple/...