Receiving a gift is never taxable.
If you are selling something you previously received as a gift, your taxable gain is the difference between the selling price and the cost basis, which is usually the price the giver paid.
Capital gains stack on top of your other income. Suppose your taxable income without the gain is $90,000 and you have $10,000 of gain. The first $6000 will be taxed at zero percent but the remaining amount will be taxed at 15%.
https://turbotax.intuit.com/tax-tips/investments-and-taxes/guide-to-short-term-vs-long-term-capital-...
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