$FXN runs under the ve tokenomics popularized by Curve. Locking FXN gets you veFXN. The longer the lock time, the more veFXN received.
1 FXN locked for 4 years = 1 veFXN
1 FXN locked for 3 years = 0.75 veFXN
1 FXN locked for 2 years = 0.5 veFXN
1 FXN locked for 1 year = 0.25 veFXN