Hello Samhita, some instruments may pair with a database and it will be much easier to figure out which pit means. If there is no such database, my way is to find this Y2O3 related papers, screen out the ones with interpretation of the FTIR spectra of the Y2O3. Normally, the FTIR spectra of the Y2O3 is consistent among different researchers' work. I hope it is helpful.
I'd guess that the big absorpion above 3000 cm-1 is surface hydroxyls (or just adsorbed water). The interpretation of the strong peak around 1500 is not obvious to me. Do you have anything organic in there? Below 1000 you start to see metal-oxygen vibrations. How was the sample prepared?