What does "basic support" mean for Turbo Tax Basic on investments? It's is very vague if i can enter my stock sales or not.

Yes, you can enter your stock sales yourself. You are not required to import any sales. Follow the steps below to enter your 1099-B.

Enter the information in TurboTax by using the steps below. 

Open your TurboTax Online return:

1. Select Tax Home on the left panel > Select any Income category or Pick up where you left off
2. Select Tax Tools > Tools > Select Topic Search > Type 1099b  > Select GO (should be landed on 1099b)
3. Select Add Investments if your 1099-B is not yet present in your list
4. Continue to follow the prompts to enter the information yourself

Open your return in TurboTax Desktop:

1. Select Personal Income > Scroll to Investment Income > Select Stocks Cryptocurrency, Mutual Funds, Bonds, Other
2. Start or Update > Continue to follow the prompts to enter your 1099-B details

The sale of any investment is required to be included with your tax return, gain or loss.  Information from the link below may be helpful

• What is Form 1099-B: Proceeds from Broker Transactions?