National Financial Services is an investment firm. You may have received a Form 1099-B from them reporting the sale of an investment.
You enter investment sales in the Wages and Income section of TurboTax, then Investment Income, then Stocks, cryptocurrency, Mutual Funds, Bonds, etc... Choose Stock, Bonds, Mutual Funds as the type of investment you want to enter. You'll come to a screen where you can upload the statement from them or enter in your sales proceeds and cost basis manually.