You are definitely getting an older model from at least 2017 based on the i7 Intel 5th generation CPU. The most current MBAirs have an 8th generation i5 CPU.
The older model is nice since it has the old style keyboard most people like, however, the 128GB SSD is way too small. Most contributors on these forums recommend a minimum of a 256GB SSD. If you want to go with the older model because of the keyboard, then look for one with a 256GB SSD. Keep in mind you need to keep at least 20GB of storage space free for normal use, but you may need 40GB - 50GB free storage space when you upgrade to the next version of macOS.
Unfortunately the 2018 model has the dreaded butterfly keyboard which most people despise with a vengeance partly due to how it feels, but also because of the many keyboard failures associated with it. Apple has a free repair program for laptops with the butterfly keyboards:
https://support.apple.com/en-us/keyboard-service-program-for-mac-notebooks
FYI, the SSD on the 2018 model is soldered onto the Logic Board so make sure to purchase one with sufficient storage for the life of the laptop. While the 2017 and earlier models have removable SSDs, installing a third party SSD upgrade isn't without some issues when it comes to macOS upgrades and some system firmware upgrades so even with the older model it is best to purchase the laptop with sufficient storage. Definitely keep the original Apple SSD in case it is needed later.
Make sure to purchase at least one external drive to use for system backups. SSDs can fail at any time without any warning with little chance of being able to recover your data so a backup is very important.
