Monotonic preference means that rational consumer always prefers to have more of a commodity because it will give him a higher level of satisfaction.

More is preferred to less. When preferences are monotone, the consumer prefers more of both the goods. When preferences are strictly monotone the consumer preferes more of one good but not less of the other.

Therefore, a consumer will prefer a particular bundle if it will have at least more of one good but not less of the other good

If we say that bundle A has 3 units of community X and 5 units of commodity Y, where bundle B has 3 units of community X but only 2 units of commodity Y, then the consumer will prefer bundle A, because he is getting the same quantity of commodity B in both bundles but more of commodity Y in bundle A.