Type IIP supernovae (SNe IIP) exhibit a significant diversity in their explosion properties, yet the physical mechanisms driving this diversity remain unknown. In this work, we present photometric and spectroscopic observations of SN 2024abfl, a SN IIP in NGC 2146 with a directly detected red supergiant (RSG) progenitor. We find it has a low plateau luminosity (MV ~ -15 mag) and a relatively long plateau length (~126.5 days). We estimated a 56Ni mass of 0.014 ± 0.006 M⊙ from the tail luminosities, and an explosion energy of 0.21+0.03-0.02 0 . 21 - 0.02 + 0.03 foe (1 foe = 1051 erg) and a progenitor mass of 9.50+0.50-0.25 9 . 50 - 0.25 + 0.50 M⊙ from radiation-hydrodynamic modelling. The spectral evolution of SN 2024abfl is similar to those of other SNe IIP. However, SN 2024abfl exhibits much lower ejecta velocities than other SNe IIP at similar epochs. At later epochs, we find a relatively high-velocity Hα absorption feature at ~ - 4000 km s-1, possibly due to a fast-moving plume of matter in the inner ejecta, and two emission features at ±2000 km s-1, possibly caused by circumstellar medium (CSM) interaction, which indicates a mass-loss event before the SN explosion with a mass-loss rate of ~10-6 M⊙ yr-1. We also estimate the progenitor mass to be <=15 M⊙ based on nebular spectra. We conclude that SN 2024abfl is a low-luminosity SN IIP originating from a low-mass RSG progenitor.