ELI5: The Merge switches off Proof-of-Work in favour of Proof-of-Stake, reducing Ethereum's energy usage by ~99.95% and making the system more secure. This is a consensus layer change, not an execution layer change, so there is no difference to you, the user. However, it is already possible to enjoy lower fees by moving to secure layer 2 solutions!

ELI10: Akshually, during the Merge, block times are reduced from appearing on average every 13 seconds to appearing according to a fixed schedule every 12 seconds. This small increase in capacity could lead to a small decrease in fees. In any case, this would not be a significant decrease, and base layer operations will probably remain expensive for the foreseeable future.

So wen Merge? Follow along the progress towards making the Merge ready, or take a look at the current testnets #TestingTheMerge.