ものですからBecause, My excuse is, My explanation is

ものですから is a strong, slightly emphasized version of ものだから, a phrase that is used when explaining something or giving an excuse for one's reasoning. This grammar structure can simply be thought of as an extension of から 'because', with the noun もの 'thing' having its usual role of emphasizing what is said before it. Common translations include 'because (A)', and 'the reason is (A)'.

ものですから may appear directly after verbs and い-Adjectives, or な-Adjectives and nouns that are followed with な.

Occasionally, ものですから will be abbreviated to もので, or もんで, without any change in the overall meaning. The change of だ to its conjunctive form で indicates that there is something coming after, despite the fact that what comes after may sometimes be omitted if it is obvious.

Despite the slight difference in emphasis, ものだから and ものですから can be thought of as a single interchangable grammar structure in most situations.

Fun-fact

Although it is not a rule, ものですから will primarily be used when explaining one's actions, as a way of emphasizing that the situation of (A) specifically led to the speaker doing (B).