How is it possible for a Yisrael to have no relatives?
Rashi and Targum Yonasan: The Pasuk means relatives who have the means to redeem the field. 1
Torah Temimah (citing Kidushin, 21a): Or who does not want to redeem it, since he is under no obligation to do so).
What does the word "u'Matza" mean?
Rashi (in Bamidbar 11:22): It means that he obtains the means.
Torah Temimah (citing Erchin, 30b): It precludes selling a distant field in order to redeem one that is close or selling a poor-quality field in order to redeem a better-quality one. 1
Since "u'Matza" implies that he obtains the means now and not that he already had it.