The second kind of irregularity in the present happens by changing the ‘o’ to ‘ue’. Check out the conjugation of the verb contar (to count, to tell).

Yo cuento
Tú cuentas
Él/ella/usted cuenta
Nosotros contamos
Vosotros contáis
Ellos/ellas/ustedes cuentan

The same happens with the following verbs:

Acordar (to remember)
Acostar (to lie down)
Almorzar (to have lunch)
Aprobar (to pass a test)
Colar (to sift)
Colgar (to hang)
Consolar (to console)
Costar (to cost)
Encontrar (to find)
Engrosar (to thicken)
Forzar (to force)
Mostrar (to show)
Probar (to prove, to taste, to try)
Recordar (to remember)
Renovar (to renew)
Soltar (to let go)
Sonar (to ring)
Soñar (to dream)
Tostar (to toast)
Volar (to fly)
Volcar (to knock over, to tip)

Nos vemos prontito.