An admonition is effectively a judicial warning.
A conviction is recorded, but beyond that there is no substantive penalty for the accused. After an admonition, the accused is free to go and the case is at an end.
It is common (particularly in the Justice of the Peace Court) for the accused to be admonished following a deferral of sentence for several months, during which the accused has “been of good behaviour” (i.e. not been charged or convicted of any other offences in the interim).