塘 is a bound form (b.f.) that rarely appears alone; it serves as a morpheme in compound nouns referring to small bodies of water (pond, pool) or raised earthen structures (embankment, dike). You will encounter it in words like 池塘 (pond), 荷塘 (lotus pond), and 塘坝 (dam). As a bound form, it attaches after another noun or classifier character.