Your Adjusted Gross Income for tax year 2023 is on the 2023 federal tax return Form 1040 Line 11
See this TurboTax support FAQ for the AGI - https://ttlc.intuit.com/turbotax-support/en-us/help-article/internal-revenue-service/find-last-year-agi/L0SiDtTNI_US_en_US?uid=m9j2aqf5