Hello! That's a great question, as the composition of half dollars from that era can be a bit confusing.
The vast majority of 1974 Kennedy half dollars are not actually made of silver and are generally worth their face value of 50 cents. The U.S. Mint stopped putting silver in circulating half dollars after 1970. The standard coins minted in 1974 for circulation are made of a copper-nickel "clad" composition. If you have a regular 1974 half dollar from the Philadelphia mint (which has no mint mark) or the Denver mint (with a "D" mint mark), it is worth 50 cents. If it's in brilliant, uncirculated condition, a collector might pay a small premium, perhaps a dollar or two.
However, there is an important exception. In 1974, the San Francisco Mint did produce special collector versions of the coin that contain 40% silver. To see if you have one of these, you'll need to look for a small "S" mint mark on the front of the coin, just below President Kennedy's portrait. These 1974-S coins were not intended for circulation and were sold in special mint sets and proof sets.
The value of a 1974-S 40% silver half dollar is tied to the price of silver and fluctuates daily. Generally, its "melt value" is in the range of $3 to $5. Proof versions, which have a shiny, mirror-like finish, might fetch a dollar or two more than that. So, the key is to check for that "S" mint mark to see if you have the more valuable silver version!
(Please note that the provided context was not sufficient to answer this question, so this information is based on general numismatic knowledge.)
