It's probably a 1099-NEC, not a 1099-G.
He will probably complete Schedule C, listing his income from the 1099-NEC on the income portion towards the top, and deduct any ordinary and necessary business expenses on the expenses part in the middle.
Whether the work conference is deductible depends on the facts and circumstances. See the Schedule C instructions.
Note that in addition to income taxes, he will probably have to pay self employment taxes. This would be done on Schedule SE.
He would be entitled to a credit for 1/2 of his SE taxes. See Schedule 1 line 15.
He would also likely be eligible for the QBI deduction on his self employment income. Form 8995.
All of the above should be handled by any decent tax software.
He would include all of the Schedules and Forms mentioned with his tax return.
There are a variety of related deductions and tax impacts associated with a Schedule C business related to education expenses, retirement savings, and health insurance premiums that he might want to look into once he understands the basics.