“Part of it may be that I got very nervous and tongue-tied, but I think it’s really that I couldn’t speak very well because I don’t know enough words.”
part = 一部
get nervous = 緊張する
tongue-tied = 「舌が絡まってしまった」、言葉が上手く出ない
don’t know enough ____ = ___の知識不足
a factor = 影響を与える事の一つ