What do the remarks of this metar mean? "RMK SC1SC5AC1 AC TR SLP116"
So the posted parts means the following:

  RMK    = REMARKS   
  SC     = Stratocumulus Clouds
  1      = 1/8 (0/8 = no clouds / 8/8 = overcast clouds)`
  SC     = Again Stratocumulus Clouds
  5      = 5/8
  AC     = Altocumulus Clouds
  1      = 1/8
  AC TR  = Traces of Altocumulus
  SLP116 = Sea Level Pressure of 1011.6 mBar (just add a 10 before the given number and divide by 10)


Cloud Types:


Ac-Altocumulus
As-Altostratus
Cb-Cumulonimbus
Cc-Cirrocumulus
Ci-Cirrus
Cs-Cirrostratus
Cu-Cumulus
Fc-Fractocumulus
Fs-Fractostratus
Ns-Nimbostratus
Sc-Stratocumulus
St-Stratus


(Source: Wikipedia)

Octas:



(Source: Navcanada)