The second-largest regular group of French verbs ends in -ir in the infinitive: finir (to finish), choisir (to choose), réussir (to succeed). Drop -ir and add -is, -is, -it, -issons, -issez, -issent — noticeably heavier endings than the -er group, and this time each form does sound different.
Finir conjugates as je finis, tu finis, il/elle finit, nous finissons, vous finissez, ils/elles finissent. Watch for the -iss- that appears in the nous, vous, and ils/elles forms but not in the singular — it's a reliable sign that a verb belongs to this regular -ir pattern rather than to one of the many irregular -ir verbs (like partir or venir) that conjugate completely differently.