During transcription process in the nucleus, the information for synthesis of a particular protein is copied on to mRNA.
mRNA then leaves the nucleus with this information in code, and enters the cytoplasm and attaches to a ribosome. Ribosome are the "work benches" of the cell and it is here that proteins are made.
In the ribosome, transfer RNA or tRNA recognizes a triplet of bases e.g. GCA on the attached mRNA and decodes it. This is called the translation process. Once tRNA has determined which amino acid corresponds to that triplet, it fetches that amino acid from the pool of free amino acids in the cytoplasm and into the ribosome where it is linked with other amino acids into a chain to form the protein.