Sloka Yatha Dhenu Sahashtreshu Vatso is a famous sloka taken from Bhagwat Gita. This Sloka puts light on importance of good karmas in ones life. Hinduism and Buddhism speaks highly on Importance and laws of Karmas. Everything that happens in the world has its cause, it never happens by chance; Therefore, what we do now will have an effect on our present lives or our future lives. For this reason, people need to understand the law of Karma in order to know how to keep their words and to check their actions everyday so that everyone can find a way to create good causes at present and will get good effects in future. We have to consider that all our thoughts and actions have consequences that will ripen sooner or later. 

Yatha Dhenu Sahashtreshu Vatso Vindati Maataram
Tathaa Poorva Kratam Karma Kartaar-manugachhati

यथा धेनु सहस्त्रेषु वत्सो विन्दति मातरम् ।
तथा पूर्वकृतं कर्मं कर्तारमनुगच्छति ।।

Just as a calf can find it's mother in a herd of thousands of cows ( Dhenu ), Your Karmas follows you in every birth you take. But it also means that one's deeds decides ones karmas. What ever we do doesn’t go un-noticed good or bad. The best way to control your karmas is to control your deeds.

जैसे हजारों गायों में भी बछड़ा अपनी ही मां के पास जाता है, उसी तरह किया हुआ कर्म कर्ता के पीछे-पीछे हमेशा जाता है । हमारे किये हुए कर्म का फल हमें हमेशा मिलेगा । हर किये हुए अच्छे बुरे कर्म का फल हमें किसी न किसी जन्म में अवश्य भोगना होगा । श्लोक का सार है कि अच्छे कर्म कीजिये व् आपके साथ भी हमेशा अच्छा ही होगा।