Transcription is the first step of DNA. A segment of DNA is copied into RNA by the enzyme RNA. Both DNA and RNA are nucleic acids.
Translation is the process of translating the sequence of a messenger RNA molecule to a string of amino acids in protein synthesis. The genetic code tells you the relationship between the string of base pairs in a gene and the partnering amino acid string.
The outcome of a mutation is an alteration of the amino acid string of a protein. This alteration occurs during translation because ribosomes read the mRNA strand in terms of codons, or groups of three nucleotides.