A tRNA isoacceptor is a member of a group of tRNAs with different anticodons but which accept the same amino acid.
An anticodon is a small region on transfer RNA (tRNA) that comprises of three bases which are complementary to a codon in messenger RNA (mRNA). A codon is simply a set of three nucleotide bases.
If a codon in mRNA is GGG, the anticodon on tRNA for this will be CCC. The codon GGG is the code that calls for the amino acid called glycine.