What is translation?

Translation is the second half of protein synthesis. 

DNA is essentially a huge instruction manual on how to make each of the proteins that are needed to create the organism it belongs to.  You can think of each gene as an individual recipe.  During protein synthesis, this "recipe" is converted into an actual protein.  The first step is called transcription.  During this stage, a copy of the portion of the DNA that carries the particular gene of interest needs to be copied onto the mRNA, or messenger RNA.  In Eukaryotes, which keep their DNA in the nucleus, transcription occurs within the nucleus.  Once transcription is complete, the mRNA molecule leaves the DNA and travels to a ribosome (made of rRNA and protein) where it will be translated.  The ribosome basically reads the instructions on the mRNA three bases (C, G, A, and U) at a time (every three equals one codon).  Each codon is the instruction for one specific amino acid, which the tRNA (transfer RNA) brings to the ribosome.  The ribosome then joins these amino acids together to form the protein.